Lyten's Advancements in Lithium-Sulfur Batteries for Electric Vehicles

Lithium-sulfur batteries is an attractive battery technology, beyond the current Li-ion batteries with many advantages including high specific energy, low cost, improved safety, abundant raw materials that are not plagued by supply chain issues, and low carbon footprint. Yet, their implementation in industry has been challenging, despite impressive results in the academic environment, deterred mainly by the ‘polysulfide shuttle’ – a phenomenon attributed to the dissolution of polysulfides in electrolyte. To address this, Lyten has developed a unique family of 3D Graphene (3DG) materials from the cracking of hydrocarbons to produce hierarchical porous structure which can mitigate shuttle effects by physical entrapment of polysulfides. With its well-engineered pore structure with controlled nano/micro/meso pores providing high pore volume, Lyten 3D graphene can accommodate high proportions of sulfur and can improve retention of the polysulfide intermediates during cycling. Furthermore, its mechanically flexible framework counters the volume change of sulfur, and its high electronic conductivity overcomes the poor conductivity of sulfur and polysulfides. With the 3D graphene-sulfur cathode active material, Lyten has been fabricating high areal capacity cathodes using aqueous binders on industrial coaters. In parallel, Lyten is also developing other cell components, e.g., novel protected Li composite anodes including 3D architectures, advanced stable electrolytes that can function at electrolyte/sulfur ratios, and multi-functional separators that can block polysulfide crossover to the anode. Integrating these cell components and utilizing semi-automatic cell assembly lines, Lyten is making prototype cylindrical and pouch Li-S cells of 2-10 Ah, which show specific energies of 250-325 Wh/kg and cycle life of 250-300 cycles at C/3 and 100% depth of discharge (DOD), over 500 cycles at 50% DOD, >1000 cycles at 30% DOD and over 3000 cycles at 20% DOD in LEO (Low Earth Orbit) satellite tests. Safety tests performed on these cells, including internal short through nail penetration, external short, overcharge and over-discharge and crush showed impressive abuse tolerance without thermal runaway. In this paper, the highlights of our recent advances in the materials and component development, and the performance of cylindrical and pouch cells will be presented.